Music21 has released its first Alpha for download. The site is up at http://web.mit.edu/music21/. As an alpha release many of the features are not yet enabled and the documentation is not complete, but don't expect it ever to be since we're constantly expanding and developing the code. We plan on keeping the main syntax for Notes, Chords, and Streams exactly as it is -- it's been over two year's worth of work and refinements to get it where it is, and I think you'll be pleased. MusicXML import and export are quite well-developed and most rudimentary Humdrum/Kern support is there. Join the music21 mailing list at Google Groups to give feedback and ask questions.